Bell failed to catch his only target in Sunday's 19-9 loss to the Lions.
The Dolphins placed Sieler (biceps) on injured reserve Tuesday.
McCord will step in as the Dolphins' starting quarterback beginning with Sunday's game at Indianapolis after Miami placed Malik Willis (core) on injured reserve Tuesday, Cameron Wolfe of NFL Network reports.
The Dolphins placed Willis (core) on injured reserve Tuesday.
The Dolphins are expected to place Willis on injured reserve after an MRI on Monday revealed a core-muscle injury, Tom Pelissero of Netflix reports.
Sieler ruptured his biceps during Sunday's 19-9 loss to the Lions and will require season-ending surgery, Adam Schefter of ESPN reports.
Allen caught a 46-yard pass in Sunday's 19-9 loss to the Lions. He rushed one time for minus-one yards.
Gonzalez went 3-for-4 on field-goal tries during Sunday's 19-9 loss to the Lions.
Dulcich caught two of four targets for 14 yards in Sunday's 19-9 loss to the Lions.